It is desirable to include an anti-corrosion agent in detergent compositions to inhibit the corrosion and discoloration of metal wash baskets in automatic washing machines and to prevent the discoloration of fabrics which come in contact with the wash baskets.
Unbuilt heavy-duty liquid detergent compositions containing minor amounts of fatty acid corrosion inhibitors are known in the art. For example, see U.S. Pat. No. 4,075,118, issued to Gault et al on Feb. 21, 1978, and U.S. Pat. No. 4,079,078, issued to Collins on Mar. 14, 1978, the disclosures of which are incorporated hereby by reference.
The use of aromatic triazoles, including benzotriazole, as corrosion inhibiting agents is also known in the art. U.S. Pat. Nos. 2,618,606 and 2,618,608, granted to Schaeffer on Nov. 18, 1952, incorporated herein by reference, disclose their use primarily in built detergent compositions, although they are also said to be effective in unbuilt detergent compositions.
The present invention embodies an improved corrosion inhibiting system, consisting essentially of a mixture of an aromatic triazole and an oligomeric C.sub.14 -C.sub.22 olefinic fatty acid, for use in unbuilt heavy-duty liquid detergent compositions. It has been discovered that the combination of these corrosion inhibiting agents results in greater corrosion inhibition than that provided by each individual agent.
It is an object of this invention to provide stable unbuilt liquid detergent compositions which exhibit excellent pretreatment and through-the-wash fabric cleaning while delivering improved corrosion inhibition in automatic washing machines.